Introduction
Throughout the world, energy conservation is ranked as a high priority on the environmental agenda. Because of its large share of overall energy consumption (30-40 per cent) and the potential for economic improvements, the property presents a major energy conservation opportunity ([1] Georgopoulou et al. , 2006; [22] McGregor, 1994; [9] Hanemann and Farrell, 2006; [28] UNEP, 2007).